A conventional drive system for an induction motor for a railroad vehicle is disclosed, for example, in Patent Literature 1 below. It is mentioned in Patent Literature 1 that the drive system includes a plurality of sets of power supply sources that include power supply devices that generate direct-current power and power accumulating devices (power storage devices) that are connected in parallel to the outputs of the power supply devices to supply and accumulate direct-current power, the sets of power supply sources are connected, via open/close-controllable switches, to inverter devices that receive individual supplies of electric power via the direct-current output units, and, when the power supply source that is electrically set to an open state by the switch is connected to the power supply source on the connection partner side, the drive system monitors the direct-current output voltage of the power supply source in the open state and the direct-current output voltage of the power supply source on the connection partner side and connects the power supply source in the open state when the voltage difference between both the direct-current output voltages is equal to or lower than a predetermined differential voltage.